[elevanation]

It's a good question, yet I would propose the question itself is limiting. Being efficient includes being accurate and correct, as much as possible, over and over again, and such skills are developed with consistent practice, not with any "hacks", and usually taking more than a day.

As basic as they sound, my top 3 here are: Priority planing, execution management, and psychological self-management.

These do take more than a day to learn and implement, and after that, you are the most amazing professional possible.